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Today I came across a picture of a laptop motherboar (below).
I noticed three strange looking small footprints, labelled PJ12, PJ36 and PJ37.
The J may stand for jumper, and on the top left corner there is a PJ8 that appears to be covered with a blob of solder.

If that's the case, why are they using that weird shape?
Two adjacent plain square pads wouldn't also do the job?
Why bother taking so much space?

motherboard picture

valerio_new
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    From what I see in the picture, PJ12 and PJ36 aren't just connecting signal routes, they are actually connecting entire polygons together, therefore the increased width. The geometry used is a little bit quicker to solder than having rectangular pads, all you need is to drop a blob over it and look away (tad less manpower required = tad more profit), also the total resistance of the connection should be a bit lower as well. I have never seen such a thing "in the wild" before so I'm not 100% sure. – Vicente Cunha Jun 24 '18 at 16:01
  • PJ12 looks like it's associated with a DC/DC converter that isn't populated on this board -- the capacitor and inductor are a huge tipoff. –  Jun 24 '18 at 23:55

1 Answers1

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Solder Jumpers

Reason not sure why so big but yes they are solder jumpers for sure.

sometimes used to isolate a few MCU pins which might be conflicting otherwise connected during programming (ex.: Boot loader) for example, when sharing boot loader pins and programming pins.. So, once programming is done, a quick solder wave will join the joints later.
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User323693
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  • In this case they were never soldered, given the width and the contribution from @Vicente above, i guess they're there for delivering power to optiona peripherials or something like that – valerio_new Jun 24 '18 at 16:51
  • also, i can guess of optional ground isolation. for example DGND and AGND might be shorted only via back to back connected diodes.. depending on use case or performance later, these jumpers may effectively short the grounds. – User323693 Jun 24 '18 at 16:53